HYDROXYAPATITE-COATED PROXIMAL INGROWTH FEMORAL STEMS - A MATCHED-PAIR CONTROL STUDY

A matched pair study of 2 groups of 42 uncemented total hip replacemen ts were compared retrospectively after a minimum 3-year followup. Fort y-two hips were implanted with a hydroxyapatite coating on the proxima l femoral patched porous surfaces; 42 hips had patched porous-coated s tems without hydroxyapatite. There were no clinical differences betwee n the matched groups by any criteria of measurement. There was no stat istically significant difference between the matched groups for femora l stem fixation at all followup intervals. At the 3-year folIowup, 90% of the femoral stems in the hydroxyapatite porous group, and 83% in t he porous control group achieved stable bony fixation. Hydroxyapatite- coated femoral stems demonstrated accelerated bone remodeling characte rized by proximal cancellous hypertrophy. The percentage of femoral st ems exhibiting cancellous hypertrophy was significantly greater at all followup intervals. This study did not demonstrate any clinical advan tage of hydroxyapatite being added to a porous-coated surface. The rad iographic changes of bone remodeling seen with hydroxyapatite are not known to improve durability of the hip arthroplasty. This study again condemns the use of patched porous-coating and titanium-bearing surfac es.